JP2013242007A - Link actuation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light and compact link actuation device eliminating the need of performing extra working for the absorption of displacement on an inserted article which is inserted inside and arranged, and the need of providing a large displacement absorbing member.SOLUTION: A link actuation device 1 has link hubs 2 and 3 arranged on the input/output sides, respectively, and a plurality of sets of link mechanisms 4A and 4B. The link mechanisms 4A and 4B are three-joint chain link mechanisms comprising four revolute pairs. End links 5 and 6 are connected in a rotatable manner to the link hubs 2 and 3, and the input-side and output-side end links 5 and 6 are connected in a rotatable manner to a central link 7. The revolute pair axes O1A, O1B, O2A, and O2B of the link hubs 2 and 3 and the end links 5 and 6 are inclined toward the opposing link hubs 3 and 2. Spherical link centers P1 and P2 are located between a posture change center O and the link hub surfaces F1 and F2.

Description

  The present invention relates to a link actuating device that is used when, for example, performing complicated processing in a three-dimensional space in an articulated part of a robot, industrial machinery, etc., and handling of an article, etc., in a wide range, at high speed and precisely. About.

  As the above link actuating device, the link hub on the input side and the link hub on the output side are connected by a three-bar chain link mechanism consisting of four rotating pairs, and the attitude of the link hub on the output side is changed with respect to the link hub on the input side A possible configuration has been proposed (for example, Patent Document 1). The three-joint link mechanism consisting of four rotating pairs consists of input and output end links rotatably connected to the input and output link hubs, and the input and output end links. It consists of a central link rotatably connected to the link. Patent Document 1 discloses an example in which the input side portion and the output side portion with respect to the central portion of the central link are in a mirror image symmetry shape and a point symmetry shape in a geometric model expressing the link mechanism as a straight line. Examples are disclosed.

  The conventional link actuator including the above-mentioned Patent Document 1 has three sets of link mechanisms. This is because the minimum number of link mechanisms required to define the attitude of the output side link hub with respect to the input side link hub when the link mechanism is constituted by only links is three sets.

Japanese Patent No. 3638048

  The link actuating device is used, for example, for passing a bendable insert through a hollow portion formed inside each link mechanism and adjusting the bending angle of the insert. Inserts are extremities, such as various tubes, a person's arm, and a leg, for example. In that case, the insertion object is connected to the input side and output side link hubs of the link actuating device, and the bending angle of the insertion object is adjusted by changing the attitude of the output side link hub with respect to the input side link hub.

  The posture change of the output side link hub with respect to the input side link hub is performed by changing the rotation angle of the end link with respect to the link hub in each link mechanism with the spherical link center as the bending center. For this reason, if the attitude of the output side link hub with respect to the input side link hub is changed, displacements in the axial direction and the radial direction are generated in the connecting portion between the insert and the link hub. This will be described with reference to FIG.

  In FIG. 11, the spherical link centers on the input side and the output side are P1, P2, the link hub central axes on the input side and the output side are C1, C2, and the posture change center of the link actuator is O. The link pairs of the link mechanisms and the end links of the link mechanisms of the link mechanisms are in a relationship of intersecting each other, and the intersections are the spherical link centers P1 and P2. The link hub central axes C1 and C2 pass through the spherical link center P1 (P2) of one link hub and the other link hub when the angles formed by the link hub and the end link are the same on the input side and the output side. Is an axis extending toward the spherical link center P2 (P1). The posture change center O is an intersection of the link hub center axes C1 and C2.

  As shown by the solid line, when the angle formed by the input side link hub central axis C1 and the output side link hub central axis C2 is 0 °, the distance between the posture change center O and the spherical link hub centers P1 and P2 is Both are L0. As shown by the broken line, when the angle formed between the input side link hub central axis C1 and the output side link hub central axis C2 is θ °, the distance between the posture change center O and the link hub centers P1 and P2 is both Lθ. Here, a relationship of L0 = Lθ * cos θ is established between L0 and Lθ. Therefore, L0 <Lθ. That is, when the attitude of the output side link hub with respect to the input side link hub is changed, the distance between the attitude change center O and the link hub centers P1 and P2 changes, so that the connecting portion between the insertion object and the link hub is pivoted. Directional and radial displacements occur.

  In order to absorb the displacement and prevent an excessive force from acting on the inserted article, the following measures are taken. When the inserted material is a tube, for example, the tube is formed in a bellows shape so that it can be expanded and contracted. Further, when the inserted object is a human limb, for example, a displacement absorbing member that slides in accordance with the displacement and absorbs the displacement is provided at the connecting part of the inserted object and the link hub. When the distance between the spherical link centers P1 and P2 on the input side and the output side is long, the amount of displacement increases, so that the bellows-like portion of the tube is lengthened and the size of the displacement absorbing member is increased so as to cope with a large displacement. It is necessary to do. However, lengthening the bellows-like portion of the tube takes time and effort. Further, when the dimension of the displacement absorbing member is increased, the link actuating device becomes large and heavy.

  An object of the present invention is to provide a lightweight and compact link operating device that does not require extra processing for absorbing displacement in an inserted article that is inserted through the inside and that does not require a large displacement absorbing member. Is to provide.

In the link actuating device of the present invention, the end links are rotatably connected to the link hubs arranged on the input / output sides, and the input and output end links are rotatably connected to the central link. By doing so, a plurality of sets of three-joint link mechanisms composed of four rotary pairs are formed, which are constituted by the input end link, the central link, and the output end link. In the link actuating device having this configuration, the rotation pair central axis of the link hub and the end link is inclined toward the opposite link hub, and the spherical link center is between the posture change center and the link hub surface. It is characterized by being located.
Note that the rotational pair center axes of the link hub and the end link of each link mechanism are in a positional relationship where they intersect each other, and this intersection is the spherical link center. The link hub central axis is an axis extending through the spherical link center of one link hub toward the spherical link center of the other link hub in a state where the input side and output side link hubs are parallel to each other. It is. The posture change center is a point where the link hub central axes on the input side and the output side intersect with each other in a state where the input side and output side link hubs are not parallel to each other. The link hub surface is a plane perpendicular to the link hub central axis, including a portion where the position of the link hub in the link hub central axis direction is closest to the posture change center.

  According to this configuration, each of the input side and output side of the link hub and the end link connected thereto constitutes a spherical link mechanism, and each spherical link mechanism has end links on the input side and output side. They are connected via a central link. In this structure, the posture of the output-side link hub can be changed with two degrees of freedom with respect to the input-side link hub, and the movable range of the posture change can be widened. For example, the maximum bending angle between the input side link hub central axis and the output side link hub central axis can be 90 ° or more, and the output side link hub turning angle with respect to the input side link hub is 0 °. It can be set in the range of ~ 360 °.

  When the rotation hub center axis of the link hub and end link is inclined to the opposite link hub side, and the spherical link center is located between the posture change center and the link hub surface, Compared to the case where the axis is perpendicular to the link hub central axis, the distance between the spherical link center and the posture change center is shortened. Further, the distance between the spherical link centers on the input side and the output side is also shortened. Thereby, when changing the attitude | position of the output side link hub with respect to the input side link hub, the displacement of the connection part of the insertion thing penetrated inside each link mechanism and a link hub can be made small. Therefore, when the insert has a structure that absorbs the displacement, the insert does not need to be greatly expanded and contracted, and processing is easy. In addition, when a displacement absorbing member that slides in accordance with the displacement and absorbs the displacement is provided at the connecting portion between the insertion object and the link hub, the size of the displacement absorbing member can be small, and the link actuator can be made compact and lightweight. it can.

In the present invention, the input side end link and the central link rotation pair of the central link, and the output side end link and the central link rotation pair of the central link may be parallel to each other.
According to the spherical link mechanism, the rotation pair central axis of the end link and the central link passes through the spherical link center. By making the rotation pair central axis parallel to each other on the input side and the output side without being inclined to the link hub side, the distance between the spherical link centers on the input side and the output side can be shortened. Further, if the rotation pair center axis is parallel to the input side and the output side, the axes connecting the end link and the center link are also parallel to each other on the input side and the output side, thereby facilitating the processing of the center link. Thereby, the position accuracy of the processing is improved, and the processing cost can be reduced.

In the present invention, there are two sets of three-joint link mechanisms composed of the four rotary pairs, and these two sets of link mechanisms rotate the link hub and the end link on both the input side and the output side. It is assumed that the circumferential position of the paired central axis is not 180 degrees from each other, and the input side end link and the output side end link are connected to at least one of the two sets of link mechanisms. It is preferable to provide interlocking means for rotating and displacing in conjunction with each other so that the rotation directions are opposite to each other and the rotation displacement angles are the same.
When there are two sets of link mechanisms, it is possible to secure a wide opening of the link hub for inserting the inserts inserted into the inside of each link mechanism into the link hub, so that the inserts can be taken in and out of the link hub. It becomes easy. Therefore, it is possible to reduce the size of the link actuating device relative to the insert. Further, interference between the link members of the plurality of link mechanisms is reduced, and the operating angle of the link operating device can be increased. For this reason, usability is improved.

  When there are two sets of link mechanisms, the two central links of each link mechanism have one degree of freedom limited to translational movement on the circumference of the circle on which the respective spherical link mechanisms overlap. The spherical link mechanism on the input side and the output side is a four-bar linkage mechanism on a plane if the radius of curvature of the node is infinite, and each of the input side and the output side has one degree of freedom independently. . When there is no interlocking means between the input side and output side end links, there are 3 degrees of freedom with 1 degree of freedom for the two central links and 1 degree of freedom for the spherical links on the input side and the output side. Here, when an interlocking means is provided between the input side and output side end links, the spherical link mechanisms on the input side and the output side are interlocked, and both spherical link mechanisms provide one degree of freedom. As described above, this link actuating device is a two-degree-of-freedom mechanism that combines one degree of freedom of the central link and one degree of freedom of the spherical link mechanism. Note that the positional displacement of the central link changes between the input side and output side link hubs, and the angle between the input side and output side link hubs can change in two directions.

The interlocking means includes a first spur gear whose rotation center axis coincides with the rotation pair center axis of the input side end link and the center link, and the rotation center axis of the output side end link and the center link. It is good also as a structure which has the 2nd spur gear which is in agreement with the rotation pair central axis of this, and meshes with the said 1st spur gear.
Since the spur gear is less expensive than other gears such as bevel gears, the manufacturing cost of the interlocking means can be reduced. Further, since the spur gear is not required to have high mounting accuracy in the axial position, it can be easily assembled.

In this invention, you may provide the limiter which limits the relative rotational angular displacement of this rotation pair in at least one rotation pair of the four rotation pairs in the said link mechanism.
By limiting the relative rotational angular displacement of the rotational pair by the limiter, the movable range of the output side link hub with respect to the input side link hub is limited. Along with this, the movable range of the insert inserted inside each link mechanism is also limited. By changing the limiter settings, the movable range can be easily adjusted according to the condition of the inserted object.

When the limiter is provided, an elastic member that elastically limits the relative rotational angular displacement of the rotation pair may be provided on at least one of the four rotation pairs of the link mechanism.
In this case, when a load is applied to the insert, the elastic repulsive force of the elastic member can allow external force and displacement within the limiter range, and can reduce the impact load applied to the limiter. Strength improvement and wear reduction.

When the limiter is provided, an attenuation member that attenuates the relative rotational angular displacement of the rotation pair may be provided in at least one rotation pair of the four rotation pairs in the link mechanism.
In this case, when a heavy load is applied to the insert, an impact load is applied from the insert to the link hub. When the damping material is provided, the impact load is relieved, and the burden on the insert can be reduced.

In this invention, two or more sets of the plurality of link mechanisms are provided with actuators that can change the relative rotational angular displacement of at least one of the four rotating pairs, and the input side and the output You may provide the control apparatus which controls the said actuator so that the attitude | position of the other link hub with respect to one link hub in a side link hub may be operated within arbitrary movable ranges.
In this case, by controlling the actuator with the control device, the attitude of the output side link hub with respect to the input side link hub can be automatically changed to any two-direction angular position at any time.

  The actuator may be a rotary actuator. If it is a rotary actuator, the target rotation pair can be directly displaced by a relative angle. Therefore, a rotation transmission mechanism and a mechanism for converting linear motion into rotational motion are unnecessary, and the structure is simple and compact.

In the present invention, a linear motion actuator that can change a relative rotational angular displacement between the input side end link and the output side end link is provided in two or more sets of the plurality of link mechanisms. Also good.
In this case, the link structure is closed by the end link on the input side, the center link, the end link on the output side, and the linear actuator, and the rigidity of the link mechanism is increased.

When the input side end link and the central link rotational pair even axis, and the output side end link and the central link rotational pair central axis are parallel to each other, the linear actuator and the input / output The end link on the side is connected to each other around a rotation center axis with one degree of freedom via a bearing, and the rotation center axis with one degree of freedom is connected to the end link on the input / output side and the center link. It is good that it is parallel to the rotation pair even axis.
With this configuration, the input side end link, center link, output side end link, and linear motion actuator are connected with one degree of freedom of rotation, making it even more rigid and easy to manufacture and assemble. It becomes.

In this invention, when a spring element member that elastically restricts the positional relationship between the three link members constituting the link mechanism and the two link mechanism constituting members of the input / output side link hub is provided. good.
When an angular displacement occurs between the input side link hub and the output side link hub due to the weight of the device itself and the weight of the insertion object inserted inside the link mechanism, the spring element member has an elastic repulsive force. The angular displacement can be restored. Further, when the posture of the output side link hub is changed with respect to the input side link hub by the actuator, the output load of the actuator can be suppressed by compensating the load caused by the angular displacement by the spring element member. it can.

The spring element member is provided, for example, between the input-side end link and the output-side end link.
With this arrangement, it is possible to cope with the angular displacement by only expansion and contraction without twisting the spring element member. Therefore, an ordinary spring element member such as a tension spring or a compression spring should be used. Can do.

In the link actuating device, the input / output side link hubs have hollow portions penetrating along the respective link hub central axes, and limb joints are located between the input / output side link hubs, and The link hub can be mounted around the limb joint part in a state in which a portion following the limb joint part is inserted into the hollow part of the link hub.
When this link actuating device is attached to the limb joint as described above, the limb joint of a person with weak muscle strength can be held at an appropriate angle. Further, since bending with two or more degrees of freedom is possible, there is little uncomfortable feeling at rest or operation. Further, when the actuator is forcibly operated by an actuator, it can be used for operation assistance such as walking and rehabilitation in which the joint part of the limb is moved in a passive manner.

  In the link actuating device of the present invention, the end links are rotatably connected to the link hubs arranged on the input / output sides, and the input and output end links are rotatably connected to the central link. In the link actuating device having a plurality of sets of three-linkage link mechanisms composed of four rotary pairs, each link mechanism comprising the input side end link, the center link, and the output side end link. The rotational pair of the link hub and the end link is in a positional relationship where they intersect with each other, and this intersection is called the spherical link center, and the input and output side link hubs are parallel to each other, An axis extending through the spherical link center of the other link hub toward the spherical link center of the other link hub is referred to as a link hub central axis, and the link hub on the input side and the output side The point where the link hub central axes on the input side and the output side intersect with each other in a state where they are not parallel to each other is referred to as a posture change center, and the position of the link hub in the link hub central axis direction is closest to the posture change center. When a plane perpendicular to the link hub central axis is referred to as a link hub surface, the rotation pair central axis of the link hub and the end link is inclined toward the opposite link hub. Since the spherical link center is located between the posture change center and the link hub surface, it is not necessary to carry out extra processing for absorbing displacement in the inserted article that is inserted through the inside, and It is not necessary to provide a large displacement absorbing member, and is lightweight and compact.

It is a front view of the link actuating device concerning one embodiment of this invention. It is a side view of the link actuating device. It is sectional drawing which shows the connection part of the link hub and end part link of the link actuating device. (A) is sectional drawing which shows the connection part of the edge part link and center link of the same link actuator, (B) is the side view. It is a top view of the link hub of the link actuating device. It is a figure which shows the shape of the edge part link of the link actuator. It is a figure which shows an example of the use condition of the link actuating device. It is a front view of the link actuating device concerning a different embodiment of this invention. It is a side view of the link actuating device. It is a figure which shows an example of a limiter. It is explanatory drawing of the displacement of the connection part of the insertion thing and link hub in a link mechanism.

An embodiment of the present invention will be described with reference to FIGS.
1 and 2 are a front view and a side view of a link actuator according to an embodiment of the present invention. This link actuating device 1 has input-side and output-side link hubs 2 and 3, and these link hubs 2 and 3 are connected by two sets of link mechanisms 4A and 4B. In FIG. 2, only one link mechanism 4A is displayed. Each of the link mechanisms 4A and 4B is a three-barrel linkage mechanism composed of four rotary pairs, an input side end link 5 having one end rotatably connected to the input side link hub 2, and an output side link hub. 3 is composed of an output side end link 6 having one end rotatably connected to 3 and a central link 7 having both ends rotatably connected to the other ends of these end links 5 and 6.

  The two sets of link mechanisms 4A and 4B have the same geometric shape. The geometrically same shape means that a geometric model in which the link mechanism is expressed by a straight line, that is, a model expressed by each rotation pair and a straight line connecting these rotation pairs has the same shape. Each of the link mechanisms 4A and 4B has a geometric model expressed by a straight line in which the input side portion and the output side portion with respect to the central portion of the central link 7 are mirror images of each other.

  Both end links 5 and 6 on the input side and output side of the link mechanisms 4A and 4B have a spherical link structure. The spherical link structure is a rotation pair center axis O1A, O1B (O2A, O2B) of the link hub 2 (3) and the end link 5 (6), and a rotation pair center of the end link 5 (6) and the central link 7. A structure in which the axes O3A and O3B (O4A and O4B) intersect at a common spherical link center P1 (P2).

  As shown in FIGS. 1 and 2, the link hubs 2 and 3 on the input side and the output side are parallel to each other, and the other link hub passes through the spherical link center P1 (P2) of one link hub 2 (3). An axis extending toward the spherical link center P2 (P1) of 3 (2) is referred to as a link hub central axis C1 (C2). When the input-side and output-side link hubs 2 and 3 are not parallel to each other (not shown), the link hub center axes C1 and C2 intersect each other. This intersection is referred to as a posture change center O.

  The rotation pair central axes O3A and O3B (O4A and O4B) of the end links 5 and 6 and the central link 7 are parallel to each other. On the other hand, the rotation pair center axes O1A and O1B (O2A and O2B) of the link hubs 2 and 3 and the end links 5 and 6 are inclined to the opposite link hubs 3 and 2 side. Therefore, the spherical link centers P1 and P2 are located between the posture change center O and the link hub surfaces F1 and F2. The link hub surfaces F1 and F2 include portions where the positions of the link hubs 2 and 3 in the direction of the link hub central axes C1 and C2 are closest to the posture change center O and are perpendicular to the link hub central axes C1 and C2. That is.

  An angle η (FIG. 3) formed by the rotation pair center axes O1A, O1B (O2A, O2B) and the link hub center axes C1, C2 is, for example, 45 °. The rotation pair center axes O1A and O1B (O2A and O2B) of the link hubs 2 and 3 and the end links 5 and 6 and the rotation pair center axes O3A and O3B (O4A and O4B) of the end links 5 and 6 and the center link 7. The formed angle β (FIG. 6) is, for example, 90 °.

As shown in FIG. 5, the two pairs of link mechanisms 4A and 4B are in a positional relationship in which the rotation pair even center axes O1A and O1B (O2A and O2B) intersect each other. That is, the angle between the rotation pair center axes O1A and O1B (O2A and O2B) on the plane perpendicular to the link hub center axis C1 (C2) is not 180 °. The central links 7 (not shown in FIG. 3) of the link mechanisms 4A and 4B are located on the side where the inter-axis angle of the rotation pair central axes O1A and O1B (O2A and O2B) is larger than 180 °. In the illustrated example, the inter-axis angle alpha ₁ of the smaller is the 120 °. Accordingly, link hub central axis C1 (C2) and on a plane perpendicular, revolute pair center axis O1A, a O1B (O2A, O2B) and angle alpha ₂ is also 120 ° to the transverse plane of symmetry plane.

  1 and 2, the input side end link 5 and the output side end link 6 of each of the link mechanisms 4A and 4B are rotationally displaced in conjunction with each other by the interlocking means 9. . In the case of this embodiment, the interlocking means 9 includes a first spur gear 10 that rotates about the rotation pair central axes O3A, O3B of the input side end link 5 and the central link 7, and an output side end link 6. The center link 7 is composed of a second spur gear 11 that rotates about the rotation pair even center axes O4A and O4B and meshes with the first spur gear 10. The pair of spur gears 10 and 11 have the same specifications so that the input side end link 5 and the output side end link 6 have opposite rotation directions and the same rotational displacement angle. Linked to

  Thus, when the interlocking means 9 is composed of a pair of spur gears 10 and 11, the spur gear is less expensive than other gears, such as a bevel gear, so that the manufacturing cost of the interlocking means 9 can be suppressed. Further, since the spur gears 10 and 11 are not required to have a high mounting accuracy in the axial position, they can be easily assembled. The interlocking means 9 is not limited to the engagement of the pair of spur gears 10 and 11 having the same specifications. A link mechanism, a cam, a belt or the like may be used instead of the spur gear.

  In the illustrated example, the interlocking means 9 is provided in both of the two sets of link mechanisms 4A and 4B, but only one of them may be provided. Even with only one of them, it is possible to regulate the operation with two degrees of freedom described later. However, if the interlocking means 9 is provided in both of the two sets of link mechanisms 4A and 4B, the rigidity of the link actuator 1 is high, and the output side link hub 3 can be accurately positioned with respect to the input side link hub 2. Can do.

  As shown in FIG. 5, the link hub 2 (3) has an arc shape extending along a plane perpendicular to the link hub central axis C1 (C2), and penetrates in the direction of the link hub central axis C1 (C2). A hollow portion 20 is formed. The hollow portion 20 communicates with the outside of the link hubs 2 and 3 through the opening 21. The opening 21 is located on the same side with respect to the rotation pair central axes O1A, O1B, O2A, and O2B for both the input side and output side link hubs 2 and 3. That is, as shown in FIGS. 1 and 2, in the posture where the input side link hub 2 and the output side link hub 3 are parallel to each other, the opening portions 21 of both the link hubs 2, 3 both face the same side.

  At both ends of the link hub 2 (3), link connecting portions 13 to which the end links 5 (6) are rotatably connected are respectively provided. As shown in FIG. 3, the link connecting portion 13 has two rolling bearings 14 inside, and these rolling bearings 14 rotate a rotating shaft 15 provided integrally at the base end of the end link 5 (6). Support freely. The axis of the rotating shaft 15 coincides with the rotating pair center axes O1A, O1B (O2A, O2B). One end of the rotary shaft 15 protrudes from the link connecting portion 13 to the outer diameter side of the link hub 2 (3), and the base end of the end link 5 (6) is attached to the protruding portion by a key 16 so as not to rotate. ing. The rotary shaft 15 is prevented from coming off in the axial direction by sandwiching the base end of the rolling bearing 14 and the end link 5 (6) between a large diameter portion 15a at one end and a nut 17 screwed to the other end.

  In the rolling bearing 14, an outer ring 14 a is fitted to the inner periphery of the link connecting portion 13 by press fitting or the like, and an inner ring 14 b is fitted to the outer periphery of the rotary shaft 14 by press fitting or the like. The rolling bearing 14 is a ball bearing such as a deep groove ball bearing or an angular ball bearing. As the rolling bearing 14, a roller bearing may be used in addition to arranging ball bearings in a double row as shown in the illustrated example. Further, a sliding bearing may be used instead of the rolling bearing 14.

  Further, as shown in FIG. 4, two rolling bearings 18 are provided at both ends of the central link 7, and the connecting shafts 19 are connected to the ends of the end links 5 and 6 by bolts 19 a by these rolling bearings 18. Is supported rotatably. The axis of the connecting shaft 19 coincides with the rotational pair center axes O3A, O3B (O4A, O4B). In the rolling bearing 18, an outer ring 18 a is fitted to the end of the center link 7 by press fitting or the like, and an inner ring 18 b is fitted to the outer periphery of the connecting shaft 19 by press fitting or the like. The rolling bearing 18 is a ball bearing such as a deep groove ball bearing or an angular ball bearing. As the rolling bearing 18, a roller bearing may be used in addition to arranging ball bearings in a double row as shown in the illustrated example. Further, a sliding bearing may be used instead of the rolling bearing 18.

  As shown in FIG. 1, the link mechanisms 4A and 4B are provided with actuators 23A and 23B that can arbitrarily change the attitude of the input-side end link 5 with respect to the input-side link hub 2, respectively. The actuators 23A and 23B are, for example, rotary actuators, and rotate the end shaft 5 by driving the rotary shaft 15 to rotate. If the actuators 23A and 23B are rotary actuators, the rotation of the actuators 23A and 23B can be transmitted to the rotary shaft 15 as it is, and the structure is simple and compact.

  As shown in FIG. 2, a spring element member 26 is provided between the input end link 5 and the output end link 6 to elastically restrict the positional relationship between the end links 5 and 6. ing. The spring element member 26 is, for example, a tension spring. Both ends of the spring element member 26 are rotatably connected to spring connection shafts 27 respectively supported by the end links 5 and 6. The spring connecting shaft 27 is parallel to the rotational pair central axes O3A and O3B (O4A and O4B) of the end link 5 (6) and the central link 7.

  When viewed only from the operation surface, the spring element member 26 may be provided between other link mechanism constituent members other than between the input side end link 5 and the output side end link 6. The link mechanism constituent members are the input / output side link hubs 2 and 3 and the three links 5, 6, and 7. However, when the spring element member 26 is provided between the input side end link 5 and the output side end link 6 as in this example, the spring element member 26 does not twist with respect to the angular displacement. It is possible to cope with only expansion and contraction. Therefore, an ordinary spring element member such as a tension spring or a compression spring can be used. Further, if both ends of the spring element member 26 are connected to the spring connecting shaft 27 parallel to the rotation pair central axes O3A, O3B (O4A, O4B), an offset load is applied to the connecting portion of the spring connecting shaft 27 and the spring element member 26. Without increasing the spring holding strength.

  When the input-side end link 5 is rotated by the actuators 23A and 23B, the interlocking means 9 causes the input-side end link 5 and the output-side end link 6 to rotate in opposite directions with respect to the central link 7. And it interlocks so that a rotation displacement angle may become the same. Accordingly, the movement of the output side link hub 4 with respect to the input side link hub 2 uniquely determines the attitude of the output side link hub 3 with respect to the input side link hub 2. That is, the link actuating device 1 is a mechanism having two degrees of freedom of rotation in which the posture of the output side link hub is uniquely determined with respect to the input side link hub.

  explain in detail. In this structure, each of the input side and the output side of the link hubs 2 and 3 and the end links 5 and 6 connected thereto constitutes a spherical link mechanism, and each spherical link mechanism has an input side and an output side. End links 5 and 6 are connected via a central link 7. Here, the two central links 7 of the link mechanisms 4A and 4B have one degree of freedom limited to translational movement on the circumference of a circle in which the respective spherical link mechanisms overlap. The spherical link mechanism on the input side and the output side is a four-bar linkage mechanism on a plane if the radius of curvature of the node is infinite, and each of the input side and the output side has one degree of freedom independently. . If there is no interlocking means 9 between the end links 5 and 6 on the input side and the output side, 3 degrees of freedom with one degree of freedom of the two central links 7 and one degree of freedom of the spherical link mechanism on the input side and the output side. Degree. Here, in this link actuating device 1, since the interlocking means 9 is provided between the end links 5 and 6 on the input side and the output side, the respective spherical link mechanisms are interlocked, and the both spherical link mechanisms have one degree of freedom. . As described above, the link actuating device 1 is a mechanism with two degrees of freedom that combines one degree of freedom of the central link 7 and one degree of freedom of the spherical link mechanism. The positional displacement of the central link 7 changes in angle between the input-side and output-side link hubs 2 and 3, and from the above, the angle change in two directions occurs between the input-side and output-side link hubs 2 and 3. A possible structure.

  As in this embodiment, in the two sets of link mechanisms 4A and 4B, the angles and lengths of the end links 5 and 6 and the geometric shapes of the end links 5 and 6 are equal on the input side and the output side, Further, when the shapes of the central link 7 are the same on the input side and the output side, the end links connected to the central link 7 and the input and output side link hubs 2 and 3 with respect to the symmetry plane of the central link 7. 5 and 6 are the same on the input side and the output side, the input side link hub 2 and the input side end link 5, the output side link hub 3 and the output are considered from geometric symmetry. It moves in the same way as the end link 6 on the side.

  This two-degree-of-freedom link actuator 1 can widen the movable range of the output-side link hub 3 relative to the input-side link hub 2. For example, the maximum bending angle (maximum bending angle) between the input-side link hub central axis C1 and the output-side link hub central axis C2 can be 90 ° or more. Further, the turning angle of the output side link hub 3 with respect to the input side link hub 2 can be set in a range of 0 ° to 360 °. The bending angle is the inclination angle of the output side link hub central axis C2 with respect to the input side link hub central axis C1, and the turning angle is the output side link hub center C1 with respect to the input side link hub central axis C1. This is the horizontal angle at which the axis C2 is inclined.

  In addition, the rotation pair center axes O1A and O1B (O2A and O2B) of the link hub 2 (3) and the end link 5 (6) are inclined toward the opposite link hub 3 (2), as in the conventional case. The distance between the spherical link center P1 (P2) and the posture change center O is short as compared with the case where the rotation pair even axes O1A, O1B (O2A, O2B) are perpendicular to the link hub center axis C1 (C2). The distance between the spherical link centers P1 and P2 on the input side and the output side is also short. As a result, when the posture of the output side link hub 3 with respect to the input side link hub 2 is changed, the inserts (not shown) inserted inside the link mechanisms 4 are connected to the link hubs 2 and 3. The displacement of the part can be reduced.

  Each actuator 23A, 23B may be controlled manually or by the control device 24 (FIG. 1). When controlling by the control device 24, the attitude of the output side link hub 3 with respect to the input side link hub 2 can be automatically changed to an arbitrary two-direction angular position at an arbitrary time.

  When the link actuator 1 is used, the angle between the link hub 2 on the input side and the link hub 3 on the output side depends on the weight of the link actuator 1 itself and the weight of the insertion object to which the link actuator 1 is attached. Although the displacement may occur, the angular displacement can be restored by the elastic repulsion force of the spring element member 26. Further, when the posture of the output side link hub 3 is changed with respect to the input side link hub 2 by the actuators 23A and 23B, the spring element member 26 compensates for the load caused by the angular displacement, whereby the actuators 23A and 23B. The output load can be suppressed.

  The link actuating device 1 includes four rotation pairs in each of the link mechanisms 4A and 4B, that is, a rotation pair of the input side link hub 2 and the input side end link 5, and the output side link hub 3 and the output side end. The rotation pair of the link 6 and the two rotation pairs of the end links 5 and 6 on the input side and the output side and the central link 7 have a bearing structure, so that the friction resistance at each rotation pair is suppressed and the rotation resistance is reduced. Can be reduced, a smooth rotational angular displacement can be secured, and durability can be improved.

  Since the number of link mechanisms 4A and 4B is two sets, which is smaller than the conventional three sets, it is easy to avoid interference between the link mechanisms 4A and 4B, and the degree of freedom in design is high. Thereby, it is possible to have a compact configuration in which the outer diameter of the entire link actuator 1 is small. Further, since the number of link mechanisms 4A and 4B is small, cost reduction can be realized. Further, since the two sets of link mechanisms 4A and 4B have the same shape, the types of parts can be reduced, and this also realizes cost reduction.

  Moreover, when the link mechanisms 4A and 4B are two sets, a wide opening 21 for inserting the inserted material inserted into the inside of each link mechanism 4A and 4B into the hollow portion 20 of the link hubs 2 and 3 is secured. It is possible to easily insert and remove the inserted material into and from the hollow portion 20. Therefore, it is possible to reduce the size of the link actuating device 1 relative to the insert. Further, the interference between the link members 5, 6, 7 of the link mechanisms 4 </ b> A, 4 </ b> B is reduced, and the operating angle of the link operating device 1 can be increased. For this reason, usability is improved.

  The central link 7 of each of the link mechanisms 4A and 4B has an angle formed between the link hubs 2 and 3 of the two sets of link mechanisms 4A and 4B and the rotation pair even center axes O1A, O1B, O2A, and O2B of the end links 5 and 6. It is located on the side larger than 180 °. Therefore, structurally, the rotation hub of the link hub 2 and the end links 5 and 6 of one link mechanism 4A (4B) is connected to the end links 5 and 6 and the center link 7 of the other link mechanism 4B (4A). Difficult to interfere with the rotating pair of For this reason, in order to avoid the interference, it is not necessary to provide the rotation pair of the end links 5 and 6 and the central link 7 so as to extend in the outer diameter direction, and a compact configuration with a small outer diameter can be achieved.

  FIG. 7 shows a state in which the link actuating device 1 is mounted around a human knee joint for the purpose of rehabilitation, exercise assistance, and the like. The knee joint 40 is located between the input-side and output-side link hubs 2 and 3, and the portions following the knee joint 40, that is, the upper leg portion 41 and the lower leg portion 42, are formed in the hollow portions 20 of the link hubs 2 and 3. It is inserted. In this case, the person's leg 43 becomes an insertion object inserted inside the link mechanisms 4A and 4B. The upper thigh 41 and the lower thigh 42 are put in and out of the hollow portion 20 through the opening 21. A belt or the like (not shown) that closes the opening 21 may be provided so that the leg 43 does not come out of the hollow portion 20 when the link actuating device 1 is mounted.

  In a state where the link actuator 1 is mounted, the bending angle and the twisting angle of the knee joint 40 are adjusted by adjusting the rotation angle of each rotation pair of the two pairs of link mechanisms 4A and 4B by driving the actuators 23A and 23B. Can be adjusted. Further, if the rotation angle of each rotation pair of the link mechanisms 4A and 4B is fixed, the bending angle and the twist angle can be fixed. Thus, by adjusting and fixing the angle of the knee joint 40, it is possible to easily cope with different angle differences depending on the physical characteristics of the patient and the condition of the affected part. Since the input-side and output-side link hubs 2 and 3 receive loads on both sides of the affected knee joint 40, the load on the knee joint 40 can be reduced. Further, by driving the actuators 23A and 23B to forcibly change the rotation angle of each rotation pair of the two sets of link mechanisms 4A and 4B, operation assistance such as walking is performed or the knee joint is moved in a passive manner. Can be rehabilitated.

  As described above, the link actuating device 1 has a small displacement of the connecting portion between the inserted article and the link hubs 2 and 3 when the posture of the output side link hub 3 is changed with respect to the input side link hub 2. It is not necessary to provide a displacement absorbing member that absorbs the displacement between the leg 43 that is the insertion object and the link hubs 2 and 3, or a displacement absorbing member having a small size is sufficient. For this reason, the link actuator 1 can be made compact and lightweight. The link actuating device 1 can also be used by being mounted around the limb joints other than the knee.

  The link operating device 1 can also be used to insert a flexible tube or the like (not shown) inside the link mechanisms 4A and 4B and adjust the bending angle of the tube or the like. In this case, a tube or the like serves as an insert. Even in this link actuating device 1, when the posture of the output side link hub 3 with respect to the input side link hub 2 is changed, the connecting portion between the inserted article and the link hubs 2 and 3 is slightly displaced, so that the tube or the like is bellows-like. It is necessary to make the structure stretchable. However, since the amount of displacement is small, the size of the bellows-like portion can be short, and the processing is easy.

  8 and 9 show different embodiments of the present invention. In this link actuating device 51, instead of the actuators 23A and 23B in the link actuating device 1, relative rotation angles of the input side end link 5 and the output side end link 6 are connected to the link mechanisms 4A and 4B. Direct acting actuators 53A and 53B that can change the displacement are provided. The main body portion 53a and the rod portion 53b of the linear actuators 53A and 53B are attached to the end links 5 and 6 through bearings 54 so as to be rotatably supported around the rotation center shafts 55a and 56a with one degree of freedom. 56, respectively. The rotation center axes 55a and 56a are parallel to the rotation pair center axes O3A and O3B (O4A and O4B) of the end link 5 (6) and the center link 7.

  In this case, the link structure is closed by the input side end link 5, the center link 7, the output side end link 6, and the linear actuator 53A (53B), and the rigidity of the link mechanism 4A (4B) is increased. Further, since the linear actuator 53A (53B) is connected to the input side end link 5 and the output side end link 6 with one degree of freedom of rotation, the rigidity is further increased and the manufacture and assembly are facilitated.

  FIG. 10 shows a different configuration of the connecting portion between the link hub and the end link. This connecting portion is provided with a limiter 60 that limits the relative rotational angular displacement of the rotational pair of the link hub 2 (3) and the end link 5 (6). The limiter 60 includes a stopper 61 provided on the link hub 2 (3) and a pair of stopper receivers 62A and 62B provided on the end link 5 (6).

  The stopper 61 is a columnar member that protrudes from the end face of the link hub 2 (3) toward the end link 5 (6), and passes through an arc-shaped elongated hole 63 formed in the end link 5 (6). Has been. The long hole 63 has an arc shape centered on the rotation pair central axes O1A and O1B (O2A and O2B) of the link hub 2 (3) and the end link 5 (6).

  The stopper receivers 62A and 62B are respectively disposed on both sides in the circumferential direction with the stopper 61 interposed therebetween, and are attached to the end link 5 (6) so that the circumferential position can be changed. Specifically, the end link 5 (6) is provided with a plurality of screw holes 64 along the elongated holes 63, and bolts 66 inserted into the bolt insertion holes 65 of the stopper receivers 62A and 62B are inserted into the plurality of screw holes 64. By selectively screwing into any one of these, the stopper receivers 62A and 62B are attached to the end link 5 (6) so that the circumferential position can be changed. In order to prevent the stopper receivers 62A and 62B from rotating, the stopper receivers 62A and 62B are attached to the end link 5 (6) with two bolts 66. In the illustrated example, the bolt insertion hole 65 is a long hole shared by two bolts 66, but a bolt insertion hole 65 may be provided for each bolt 66.

  The stopper receivers 62A and 62B are provided with a damper 67 on the surface facing the stopper 61 side. The damper 67 is made of a spring element member such as rubber and acts to elastically limit the relative rotational angular displacement of the rotational pair of the link hub 2 (3) and the end link 5 (6). The damper 67 is an “elastic member” and a “damping material” in the claims.

  As shown in the figure, when the dampers 67 of the stopper receivers 62A and 62B are in contact with both sides of the stopper 61, the angle formed by the link hub 2 (3) and the end link 5 (6) is c °, When the angle formed by the stopper receiver 62A is a ° and the angle formed by the stopper 61 and the stopper receiver 62B is b °, the variable angle range of the end link 5 (6) with respect to the link hub 2 (3) is (c−a ) ° to (c + b) °.

  By limiting the relative rotational angular displacement of the rotational pair of the link hub 2 (3) and the end link 5 (6) by the limiter 60, the movable range of the output side link hub 3 with respect to the input side link hub 2 is limited. Is limited. Along with this, the movable range of the insertion object, for example, the limb joint part, to which the link operating device 1 is attached is also limited. By changing the setting of the limiter 60, it is possible to easily adjust the movable range according to the situation of the limb joint part which is the affected part. In addition, when an impact force is applied to the extremities, a load is suddenly applied to the extremities that come into contact with the link hub 2 (3), but a sudden load change is mitigated by the damper 67, reducing the burden on the extremities. can do.

DESCRIPTION OF SYMBOLS 1 ... Link operation apparatus 2 ... Link hub (link mechanism structural member) on the input side
3 ... Output side link hub (link mechanism component)
4 ... Link mechanism 5 ... Input side end link (link mechanism component)
6 ... Output side end link (link mechanism component)
7. Central link (link mechanism component)
DESCRIPTION OF SYMBOLS 9 ... Interlocking means 10, 11 ... Spur gear 20 ... Hollow part 23A, 23B, 53A, 53B ... Actuator 24 ... Control device 26 ... Spring element member 54 ... Bearing 55a, 56a ... Rotation center shaft 60 ... Limiter 67 ... Damper (elasticity) Member, damping material)
C1 ... Input side link hub central axis C2 ... Output side link hub central axis F1 ... Input side link hub surface F2 ... Output side link hub surface O ... Posture change centers O1A, O1B ... Input side link hub and input Rotating pair center axis O2A, O2B of the side end link O2A, O3B of the output side link hub and the rotating pair even axis of the output side link O3A, Rotating pair center axis O4A of the end link of the input side and the central link , O4B: Rotating pair center axis P1 of output side end link and central link P1: spherical link center P2 of input side: spherical link center of output side

Claims (14)

End links are rotatably connected to the link hubs respectively arranged on the input / output sides, and the input side and output side end links are rotatably connected to the central link, so that the input side In a link actuating device having a plurality of sets of three-joint link mechanisms composed of four rotary pairs, which are constituted by an end link, a center link, and an output end link.
The rotational pair of the link hub and the end link of each link mechanism is in a positional relationship where they intersect with each other, and this intersection is called the spherical link center,
An axis extending through the spherical link center of one link hub toward the spherical link center of the other link hub in a state where the input side and output side link hubs are parallel to each other is referred to as a link hub central axis,
The point where the link hub central axes on the input side and the output side intersect with each other in a state where the input side and output side link hubs are not parallel to each other is referred to as a posture change center,
When the position of the link hub in the link hub central axis direction includes the place closest to the posture change center, and a plane perpendicular to the link hub central axis is referred to as a link hub surface,
The rotation pair central axis of the link hub and the end link is inclined toward the opposite link hub, and the spherical link center is located between the posture change center and the link hub surface. Link actuating device.   2. The link operating device according to claim 1, wherein the input-side end link and the central link of the central link are parallel to each other, and the output-side end link and the central link of the central link are parallel to each other.   In Claim 1 or Claim 2, it has two sets of link mechanisms of the three-branch chain which consists of the above-mentioned four rotation pairs, and these two sets of link mechanisms are the link hub and the above-mentioned both on the input side and the output side. The circumferential position of the rotation pair of the end link is not 180 degrees from each other, and at least one set of the two sets of link mechanisms includes the end link on the input side and the output side. A link actuating device provided with interlocking means for rotating and displacing the end links of the two links in conjunction with each other so that the rotation directions are opposite to each other and the rotation displacement angles are the same.   4. The interlocking means according to claim 3, wherein the interlocking means includes a first spur gear whose rotation center axis coincides with the rotation-side center axis of the input side end link and the center link, and the rotation center axis of the output side end portion. A link actuating device comprising a link and a second spur gear which is aligned with a rotation pair central axis of the central link and meshes with the first spur gear.   The link operation according to any one of claims 1 to 4, wherein a limiter for limiting a relative rotational angular displacement of the rotational pair is provided on at least one rotational pair of the four rotational pairs of the link mechanism. apparatus.   6. The link actuating device according to claim 5, wherein at least one of the four rotating pairs of the link mechanism is provided with an elastic member that elastically limits a relative rotational angular displacement of the rotating pair.   7. The link actuating device according to claim 5, wherein at least one of the four rotating pairs in the link mechanism is provided with a damping material that attenuates a relative rotational angular displacement of the rotating pair.   The relative rotational angular displacement of at least one of the four rotational pairs can be changed to two or more of the plurality of link mechanisms according to any one of claims 1 to 7. A link actuating device provided with an actuator and a control device for controlling the actuator so that the posture of the other link hub with respect to one link hub in the input side and output side link hubs is operated within an arbitrary movable range. .   9. The link actuator according to claim 8, wherein the actuator is a rotary actuator.   8. The relative rotational angular displacement of the input side end link and the output side end link is determined in two or more sets of the plurality of link mechanisms according to claim 1. A link actuating device provided with a linear actuator that can be changed.   11. The linear motion actuator according to claim 10, wherein the input side end link and the central link rotation pair axis of the center link, and the output side end link and the rotation link center axis of the center link are parallel to each other, And the end link on the input / output side are connected to each other around a rotation center axis with one degree of freedom via a bearing, and the rotation center axis with one degree of freedom is connected to the end link on the input / output side. A link actuating device that is parallel to the rotational pair even axis of the central link.   12. The positional relationship between the three link mechanism constituent members of the link mechanism and two link mechanism constituent members among the input / output side link hubs is elastic. Link actuating device provided with a spring element member for restricting the operation.   13. The link actuating device according to claim 12, wherein the spring element member is provided between the input side end link and the output side end link.   11. The input / output side link hub according to claim 1, wherein each of the input / output side link hubs has a hollow portion penetrating along a center axis of each of the link hubs. A link actuating device that is mounted around the limb joint part in a state where the limb joint part is located and a portion that continues to the limb joint part is inserted into the hollow part of each link hub.

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